Thursday, March 19, 2009

K3 updated

My package from Elecraft finally arrived yesterday. As well as the KXV transverter interface I had ordered parts for some of the hardware mods to update my early K3 (serial number 222) to the current spec. I don't like modifying radio gear, especially modern stuff that uses SMT parts, but one of the mods was supposed to reduce distortion on the line output that I use to receive data modes, and I had seen signs of that on the waterfall traces, so I was keen to do that mod if nothing else.

One of the earliest modifications that Elecraft made to the K3 concerned the hardware AGC (HAGC), to improve the receiver dynamic range with close-spaced signals. That mod involved removing an SMT part, although Elecraft provides conventional replacements that can be added in parallel to other SMT parts for those who wish to keep the need to touch SMT parts to a minimum.

I was reluctant to touch SMT parts on my K3 at all, but the instructions for performing the mod suggested using two soldering irons simultaneously, one at each end of the part to be removed. I still have a miniature Antex soldering iron bought over 40 years ago, so I dug it out of a box in the garage. With that and my solder station I applied heat to both sides and the part came away with ease.

Flushed with my success, I was almost tempted to go the whole hog and install the SMT replacement components that Elecraft provided. But in the end I decided not to push my luck and used the leaded components. I can't honestly say I have noticed any difference having done the HAGC mod, so if you are reading this and haven't done it yet, I wouldn't worry.